I would start with Recruit a Friend.
That is 300% experience for kills and quests, up to 60th level.

Basically you want to purchase the Battlechest.
With one account already, pick up four of these.

Go into account management for the existing account.
Send your own email, an RAF invite.
Use the code emailed to you to start the account.
Once it is going, upgrade it with the battlechest.

Then log into the account management for the newly created account.
And repeat the process.

End result (A = Existing; B-C-D-E = New RAF Accounts) will be a chain:
A > B > C > D > E

I would then take the whichever toon out of Pally/Druid/Mage that can clear low instances the best...
And use them to "boost" the new accounts.

Basically go something like:
4x Druids + Booster, all in the same group.
Quest to 10th or so.
Then run something like this (levels might not be exact, since the Cata changes):
01-10 Quest
11-20 Shadowfang Keep
20-35 Scarlet Monastery
35-42 Scholomance
42-56 Stratholme
56-61 Hellfire Ramparts



Also, for every 2 levels you gain (to 60th maximum) on a referred account, you can grant a level to the referring account.
So basically if you were to boost 4 sets of toons, on BCDE with A.
D would get two extra level 60 toons from E (as would C from D, B from C and A from B).
Plus C would get another extra toon from D (based on levels received on D from E's granting).
IE, they cascade.

They won't cascade perfectly.
And E won't receive any...

In a perfect world, you'd transfer a couple of toons from A to E.
Via character transfers.

If you were to level four toons.
You'd basically get six toons at 60th on each of the accounts (except for E, who would have four... and A who would only receive 2+ via granting).



I'd recommend the versatile characters the most.
- Druids (Ranged DPS, Melee DPS, Tank, Heals)
- Paladins (Melee DPS, Tank, Heals)
- Shaman (Ranged DPS, Melee DPS, Heals)

Beyond that, anything you think might be interesting to play down the road.

You cannot have too many options, during RAF.
It is options for later on.
Also, over time you want to level these to 75th, for maximum tradeskill levels.
And add Alchemy (up to you which skills to go with) for passive gold generation via transmutes (I'm at 800k gold, primarily from transmutes).